The following terms must be intended according to the definitions given in the following meanings.
The terms “front” and “rear” and, in similar way, “in the front” and “rearward”, must be considered as referred with respect to the usual advancement direction of a bicycle.
The terms “upper” and “lower” and “downward” and “downwardly” and, in similar way, “above” and “below” and “upward” and “upwardly”, must be considered as referred with respect to the ground with the bicycle placed in the position of normal use, in the sense that lower is indicative of a relative position closest to the ground while upper is indicative of a relative position farther from the ground.
The terms “right” and “left” must be considered as referred respectively with respect to the right or to the left of a user sitting on the saddle of the bicycle.
In the manufacturing field of foldable bicycles many solutions intended to allow that the bicycle is folded with a consequent reduction of its total encumbrance are known. In fact the bicycle represents a very light, as well as a non-polluting, locomotion means, very suitable for example in the town centres, where some limitations to the circulation of motor vehicles may also be present. However, for those who do not live in town but come from considerable distances, carrying the bicycle on other transport means is usually necessary for moving on a medium-long distance and only successively the bicycle will be used to move on the desired town path. In similar way carrying the bicycle also for those who live in town and wish to reach a destination at which using the bicycle on not necessarily short ways, as, for example, parks, hillside zones, etc. can be desirable.
For example, if main movement occurs by car, the bicycle, if not folded at sizes such to allow its stowing in the boot, must be mounted on suitable supports fixed to the car. Such supports however constitute a problem as their mounting and dismounting requires considerable effort and time. Besides this the use of these supports generally affects considerably the fuel consumes of the same car. Additionally even the activity for fixing the bicycle to the supports can be difficult, mainly in the cases in which such supports are mounted on the upper part of the car roof.
For example, if the main movement is carried out by train, the transport of a traditional bicycle along with the traveller is possible only if the train is equipped with suitable cars, while the transport of a bicycle that could be reduced to sizes similar to those of a usual luggage would be easy and would be allowed.
For example, if the main movement occurs on local buses or bus the transport of the bicycle with the traveller is impossible for reasons of encumbrance of the same bicycle.
Other situations in which the supply of a foldable bicycle is advantageous are for example those in which in a block of flats does not exist a sheltered space suitable for stowing the bicycles and bringing the bicycle in the house would be difficult both from the point of view of the same transport and from the point of view of the space required to keep it within the house. Moreover the traditional bicycles are unsuitable also in case of other conditions e.g. the transport of the same bicycles on boats, mobile home or camper van.
Usually the frame of a bicycle consists of an upper horizontal tube or “top tube” and of a main longeron that connects the front semi-frame, carrying the front wheel and the handle-bar, to the rear semi-frame carrying the rear wheel and the saddle with the relative support stanchion.
Some of the prior art techniques for foldable bicycles are conceived in such a way that the frame of the bicycle is without the upper horizontal tube and that the main longeron is divided in two halves hinged to each other with an axis hinge substantially perpendicular as to the longeron. In this way the bicycle can be folded so to pass from a condition of maximum encumbrance in the configuration with front semi-frame and rear semi-frame reciprocally longitudinally aligned to a condition of minimum encumbrance in which by refolding the semi-frames sideways to one another the length of the bicycle is reduced.
Some of the prior art techniques provide a frame with telescopic structure in which there are two semi-longerons movable between the two positions in which one of the two semi-longerons is inserted inside or extracted from the second of the two semi-longerons.
A lot of the prior art techniques to obtain a compact closed structure utilize wheels of small diameter to obtain a reduction of the total encumbrance.
The patent BE628783A discloses a bicycle equipped with an articulated and foldable element that allows a reduction of the encumbrances in which the supporting structure of the rear wheel is designed to rotate around a transverse axis coinciding with the axis of the pedals in order to be able to position the rear wheel within a stanchion between the saddle and the handle-bar.
The patent NL 1016175 discloses a foldable bike comprising a frame consisting of a main frame and of an under frame in which the under frame is rotary around a fulcrum point that forms the connection between main frame and under frame and in which the pedals and the transmission mechanism remain under tension. In folded condition the saddle-holder tube is pushed downward and the under frame rotates around the fulcrum point and the saddle-holder tube acts as locking fastener preventing the reopening of the bike from its folded condition.
The patent EP 1803634 discloses a bicycle comprising a frame and a rear arm integrated in the frame in which the rear arm is made up of two horizontal arms whose close ends are articulated in correspondence of the frame and whose distal ends are connected to the ends of oblique rear arms that fix to the frame by a male-female coupling of the tube for the saddle. Also an articulation of the rear arm is provided.
The patent WO 2005080184 discloses a foldable bike comprising a frame and a hub in which the rear wheel is mounted on the frame by means of a supporting element foldable with the wheel by rotation around the hub towards the front of the bicycle.
The patent DE 4400500 (A1) discloses a frame for bicycles having a folding point that allows the folding of the supporting rear fork of the rear wheel towards the front and then upwards, leaving the frame unaltered.
The prior art techniques for foldable bicycles providing that the frame of the bicycle is without the upper horizontal tube and that the main longeron is divided in two halves hinged to one another with a hinge are not very satisfactory from the point of view of the total reduction of the encumbrance of the bicycle in the closed configuration because the encumbrance of the folded bicycle in any case involves a considerable thickness represented by that of the two reciprocally adjacent semi-frames and also a considerable total dimension represented by the maximum dimension between the length of the front semi-frame and the length of the rear semi-frame. Additionally even the encumbrance in height may result problematic due to the presence of the wheels. Besides these problems, such prior art techniques are often subjected to the occurrence of clearances at the connection hinge of the semi-frames. The presence of clearances is likely to involve a difficulty of use and manoeuvre of the bicycle. Furthermore the connection hinge is a point subject to stress and it can be subject to also sudden yielding with consequent possibility to cause accidents.
Some of the prior art techniques provide a frame with telescopic structure in which there are two semi-longerons movable between the two positions in which one of the two semi-longerons is inserted inside or extracted from the second of the two semi-longerons. Such structures prevent the bicycle from taking a configuration similar to that of a traditional bicycle because the resort to a telescopic closure system hardly makes possible the coexistence of longeron and upper tube unless they are not reciprocally parallel. The presence of frame structures with reciprocally parallel longeron and upper tube involves the execution of frame structures that have important problems of use and that are however bulky. Moreover the presence of telescopic structures can lead to the presence of clearances in the coupling between the telescopic elements as well as to the presence of blocking of the telescopic movement. The presence of dirt that accumulates in the course of time is likely to bring to locking of the telescopic movement requiring important efforts both for the opening and for the closure of the frame, or requiring a dismounting of the same for a deep cleaning. The presence of sliding elements one inside the other involves moreover the risk to damage the protective superficial painting of the frame, exposing the bicycle to the occurrence of deterioration phenomena due to the rust just in the most delicate zones of the coupling.
The solutions of the technique providing the use of wheels of small diameter have important drawbacks as the their use is restricted to solutions in which a short range mobility is required and are hardly suited to an intensive use of the bicycle or to a sporting use because the presence of wheels of small diameter involves conditions of instability and of transmission of the stresses due to the unevenness of the ground. This type of bicycles must be necessarily used on very regular and smooth surfaces and for covering medium-long distances important efforts that limit their use are required.
Many prior art techniques need particular contrives to maintain the bicycle in safety in the position of use that consist of complications of the closure mechanism and that involve additional costs necessary to the strengthening of the maintenance of the connecting joints in the desired condition when the bicycle is in the condition of use.
Many prior art techniques do not allow the use of rear shock absorbers for damping the vibrations coming from the roughness of the ground.
Some of the prior art techniques providing the use of rear shock absorbers for damping the vibrations have the disadvantage that the shock absorber is placed so that part of the pedalling energy is transferred to the shock absorber and absorbed by the same, increasing the effort necessary for the pedalling.